Questions tagged [structures]

Questions relating to or the engineering application of a device that must withstand a loading via deflection, stresses, resistance to buckling, or natural frequencies.

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35 views

Shear Stress in Shear Pin (Single shear)

Case is of a Shear Pin with Single Notch to cause single shear. Pin is All DOF constrained for half the length and the remaining half has constant shear force. The shear force immediately starts from ...
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0answers
25 views

How do we derive the equation of motion of Cantilever Beam (Euler-Bernoulli Beam)?

I know that the equation of motion of a Cantilever Beam is: $m\frac{{{\partial }^{2}}v}{d{{t}^{2}}}+EI\frac{{{\partial }^{4}}v}{d{{x}^{4}}}+P\frac{{{\partial }^{2}}v}{d{{x}^{2}}}=0$ but how do we ...
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2answers
97 views

Unable to obtain closed system of equations using method of joints

I am currently working on some code to solve 2-dimensional truss and frame problems, and I have come into an issue with one of the problems. I need to come up with a system of linear equations that I ...
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18 views

Secure loads to gearbox shafts

I have a sculpture that is designed to rotate over 3 axes at max. 30RPM and is mounted on an aluminium disc. My plan is to use 3 of these geared steppers and secure the sculpture to the Z-axis shaft, ...
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1answer
45 views

Cheap but durable design for a quick-to-assemble, portable globe?

This question has a bit of an arts & crafts / DIY flavour, but looking at those Stack Exchanges made me feel it fits better here. I have no background in any of these things, so apologies for my ...
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1answer
51 views

Do the floorboards in timber beam floors have a structural function?

Timber beam floors with perpendicular timber floorboards as indicated in the drawing below are common throughout northern Europe. The floorboards are nailed onto the beams and are quite substantial ...
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2answers
57 views

What is the easiest way to regulate the speed of a falling object?

I want to design a system that allows a 1kg metal brick to fall under gravity at variable speeds. The brick initial position is 20cm above a flat table. I want to have control on the duration (to ...
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2answers
38 views

Fixed-Free End Column Design

I am currently working on a problem where I have to design a column. The structure I am currently designing currently takes the following form, When designing the column, I know that I have to ...
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1answer
31 views

Method of joints not working on simple truss, supposed to be stable and determinant

In the process of editing the question to put better pictures of my dimensions in, I realized that how I calculated my angles was incorrect, and that is why my answers were yielding inconsistent ...
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2answers
27 views

Earthquake time history analysis

Time history analysis of earthquakes for structures, is a NON-LINEAR dynamic method correct? Then why is there also something called "LINEAR response history analysis"? What is the difference of this ...
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1answer
66 views

What is the strongest structure?

I am not an engineer, but I thought maybe this could be a very old and classic problem in structural/mechanical engineering. I need to build a support structure to hold a uniformly-distributed load of ...
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3answers
29 views

How to solve a system of second order ODE from time t = T to t = 0

I have a system of second-order ODEs $$ \mathbf{M\ddot{x} + C\dot{x} + Kx = f} $$ I want to know some good numerical methods to solve this system of the equation given the initial conditions at time $...
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1answer
40 views

Calculate whether a polycarbonate plate can withstand a certain force

I need to calculate whether a polycarbonate sheet can withstand a certain maximum force. The force is an impact force on any one point of the sheet at any given time. All I have are the Young's ...
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8answers
7k views

What are those large poles for that are always in front of US stand-alone store buildings?

Screenshot of a video where they are featured in the background: They appear to have no electronics built in, such as an electric charge station, or a parking ticket dispenser or something like that....
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1answer
43 views

Why is a paraboloid hyperboloid shape preferred on some structures?

Why is preferred on the construction of big stadium roofs and of cooling towers, per example? What is the advantage of this geometric figure that makes it more economical?
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1answer
31 views

column yielding under earthquake

In the buildings designed with strong column weak beam concept, the columns will remain elastic, their plastic deformation will be limited. but this is not true at the base of the building. i mean i ...
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1answer
53 views

Is it safe to slightly cut the edge of RCC column for passage of pipe in bathroom?

The RCC column was cut in my absence due to passage of pipe for bathroom fittings. The thickness is about 1.5 in. Will it hamper the stability of structure?
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2answers
505 views

Vocabulary: NYC Elevated Highway & Trains, Industrial Park

I'm writing a story set in NYC and trying to describe certain industrial objects. I'm having trouble with specific technical terms for the items that I've marked w/ arrows. E.g. I don't want to use ...
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1answer
23 views

Flexure Deflection - Both ends fixed (one translation free)

I have a flexure problem. One of its ends is fixed to a frame (say F1) which is stationary (no rotation & no translation) and the other end is also fixed to another frame (say F2) which can move ...
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1answer
28 views

Could a string of large offshore wind towers support a Hyperloop tube? [closed]

I live on the east coast of Australia, where a Hyperloop faces the challenges that we have a mountain range pretty much right up against the coast, where most people live. There's very little flat ...
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1answer
30 views

Elastic waves in very thin plate

Elastic waves in structural elements are described by \begin{align} \rho \frac{\partial^2 u}{\partial t^2} &= (2 \mu + \lambda) \frac{\partial^2 u}{\partial x^2} + \mu \left( \frac{\partial^2 ...
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1answer
62 views

Maximum I-beam girder S12x31.8 span

Does 200lb/in of load on a S12x31.8 over 15 feet seem reasonable? I'm having a tough time trusting the numbers. Two story house with an attic as below. Dotted lines show load bearing walls W1 and W2. ...
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2answers
223 views

Buildings sinking into the ground

My friend has proposed that the buildings in the images below have been sinking into the ground over time and that they're not planned with basements. He thinks that the bottom of the building was ...
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1answer
31 views

What calculation to find how much force before tipping over?

I was thinking of building a free standing structure out of plumbing pipe that would go flush against the wall to hang jackets and other items. Attached is a sketch of the general thought of what the ...
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1answer
52 views

Boring through joist

I just started my BEng, so I actually don't feel ready to assess real cases. Upper floor of my quite standard British terraced house. We would like to hide an existing drainage pipe which is ...
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2answers
46 views

2nd Moment of Area of a ring

This is my first question here. I am having trouble finding the 2nd moment of area of a ring with a thickness 't' and radius 'r'. I seem to be a factor of 2 out. What I do is I consider an area like ...
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1answer
53 views

Mounting outdoors camera using aluminum 5052

I designed a simple U shape 2mm sheet metal bent mount for a 4kg outdoors CCTV camera. The mount was accidentally produced from 5052-H32 Aluminum instead of 6061-T6. Is it common to use 5052 ...
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2answers
80 views

Why does stress act a point instead of on an entire area normal to the stress?

I've often heard stress acts at a point and not on an entire cross-sectional area to which the load is applied normally. Im a little confused here, Let us consider an area of cross-section ...
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164 views

Deflection Of Beam In Structural Rigid Jointed Frame

This is a recommended follow on to one of my previous questions. It was stated that I could find the deflections of a beam by idealising it as a simply supported beam and then calculating accordingly. ...
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1answer
124 views

Deflections Of Statically Indeterminate Structures

When analysing and then designing a rigid jointed, statically indeterminate structure, I can solve for all the forces and moments using the Hardy Cross (Moment Distribution) Method. However, I am ...
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2answers
74 views

Pin joint system displacement question

A pinned system comprising bars of the same material and cross-sectional area is subjected to a vertical load P. I am required to form a relationship between FAB and P. The first part of the ...
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2answers
159 views

Can a speedbump safeguard a pipeline located below?

Recently I noticed a concrete speed bumper created near my parking. On enquiring the purpose, the committee who took the decision told me that the purpose of the bumper is to safeguard an existing ...
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1answer
75 views

Drop Panel Design Above Columns?

How to design a drop panel at a column in case the column above is rotated or not aligned to the below column (see image below), the code that i am using is the ACI Code if any reference for the ...
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2answers
73 views

Design a part to straighten moment and reduce torsion

I have a configuration with two bolts and a point of force application (see figure). I understand that, if perfectly rigid, the two parts depicted in the figure will behave identically in how they ...
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3answers
95 views

How to get corrugated plastic roofing strips to span 3m for rainwater exclusion experiment without building additional ground supports?

I'm trying to build structures to exclude some percentage of rainwater on experimental plots. I have three 20ft beam supports across the plot, spaced 3m apart and held in place by 4x4 posts that were ...
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1answer
108 views

Looking to design a cantilever support to hold up an 80kg projector

I need to make a support (preferably metal) for a projector to be fixed on the wall. The projector size is: Width: 0.7m Length: 1.1m Weight: 80kg If anyone knows how i can solve this please let me ...
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2answers
130 views

Why do some guyed towers come to a point at the bottom?

Why do some guyed broadcast towers come to a point at the base. It seems that it would be more stable if each vertical bar was anchored separately rather than being balanced at one point.
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3answers
839 views

Pin support, why is there no horizontal reaction force?

I am trying to understand this problem: If we break down the 10T, they behave like this: The right end of the beam can move as much as it wants, but the left end is pinned. Why is there no ...
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1answer
427 views

Can pinned support / pin joint transfer moments in 3D?

What's an authoritative definition of whether the idealized pinned support and pin joint can transfer moments in 3D? Most sources say both of them cannot transfer moments but are apparently only ...
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1answer
37 views

Shock/Isolation mounting under tension

I want to secure a box (roughly 20kg in total) that contains electronic equipment to the underside of a flat steel structure. We can weld onto the underside. The steel structure has a high chance of ...
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0answers
53 views

Need help with FEA bar analysis problem

I'm trying to solve this which is to find the total deformation of the bar. I'm trying to implement the finite element approach, but I am getting way too large of numbers. Here is what I did in ...
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2answers
76 views

Need Help to Remove Sway from Steel Post + Glass Panels

I have spanned ~15' with 2x 10mm tempered glass panels. They're connected in the middle with a 1.5" x 1.5" 16-gauge, 316 stainless steel post filled with concrete. This post has a 316 base welded on ...
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1answer
72 views

Optimal method of attaching commercially-available heavy bag mount to finished ceiling with least risk of structural damage

Admittedly, this question is related to an earlier one on the same subject. I would like to mount a heavy bag using a system detailed in the attached picture (FirstLaw Fitness Shock Mount). The ...
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0answers
69 views

Calculating diameter of steel rod required to not bend over a given length

I want to use steel (or other material) rods to support weight over a 900mm cavity. The weight that needs to be supported is technically unknown, but I'd specify some rough guidelines as: 100KG (max) ...
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2answers
53 views

Vibration table for tests (7-200Hz) from extruded aluminium profiles bolted together - good idea (?)

I need to design a vibration table (approx. 1000mx1000mm) to test products between 7-200Hz. I was wondering if it is recommended to make the table structure from standardised, extruded aluminum ...
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2answers
150 views

How does one build a waterproof basement?

I have been doing a bunch of research online into how to build a basement that is below the water table. The common wisdom is to "not waste the money doing that" but as someone who doesn't like to be ...
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0answers
31 views

Research based bridge project? [closed]

I am a fourth year civil engineering student at IOE pulchowk, Nepal. In our syllabus one practical based curriculum called Project Engineering has been added. I, along with 5 friends, are interested ...
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1answer
64 views

compression buckling under lateral load

I'm trying to figure out what size of round tube to use for a tensegrity structure that'll probably have people climbing on it. The rigid elements are 21' steel tubes, and in normal cases they ...
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1answer
68 views

Is a bridge more stable on concrete or soil?

I understand that foundations are used in structures to support and spread the weight of the bridge over a large area. However I am struggling to understand why certain materials such as concrete are ...
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1answer
63 views

A Steel post and base question

I make solid curved wood furniture and frequently need something like a metal plate (1/8") with a (3/4" about) supporting pipe attached at 90 degrees. Welding is a little too cumbersome but I was ...